If Massachusetts legalizes gay marriage, the argument goes, the floodgates are open. Other states will have no recourse under the “full faith and credit” clause of the Constitution except to recognize Massachusetts marriages, such that one renegade state—led by a slim majority of four activist judges—will have foisted Adam and Steve’s wedding registry upon an entire nation. The conservative response is equally extreme. Anti-gay activists have hastened to stir up voters, urging passage of a constitutional amendment that would obviate the possibility of such unions anywhere in the country.

There is something alluring about exploiting an issue like this—one that taps into entrenched religious and moral differences. And polls already reveal a deep ambivalence: Most moderates and swing voters simultaneously accept homosexuality and reject the idea of gay marriage. They generally oppose persecuting homosexual conduct, while they generally support maintaining marriage as a heterosexual-only proposition. (The former numbers dropped significantly last spring—a backlash against the Supreme Court decision invalidating Texas’ gay sodomy law.) This is a minefield for the president and one he can easily avoid. There is a principled, moderate resolution to this issue, but he has thus far ignored it in favor of big rhetoric. Commentators from the conservative Andrew Sullivan to the liberal Cass Sunstein have espoused it. But the president has failed to hear it.

The federal Defense of Marriage Act, already exists, signed into law by President Clinton in 1996. One provision defines marriage as male-female only. The other attempts to eviscerate the Constitution’s “full faith and credit” clause—by giving a state the right to deny the validity of a marriage sanctioned by a sister state. DOMA may well be unconstitutional, and this will likely be tested in the courts in the coming years.

The way to avoid that fight is to make it constitutional, say the conservatives, by amending that document. This solution ignores one legal truth and one political truth: The legal truth is that conservatives never needed DOMA in the first place—hysterical posturing notwithstanding, it’s by no means a given that other states would be forced to recognize Massachusetts marriages. For one thing, there is an established trapdoor to the full faith and credit clause: The courts have long held that no state should be forced to recognize a marriage sanctioned by another state if that marriage offends a deeply held public policy of the second state. States have been permitted to refuse to recognize marriages from states with different policies toward polygamy, miscegenation, or consanguinity for decades. At this point, 39 states have passed mini-state-sized DOMAs that proscribe marriage for gay couples, often elaborately saying that it violates their public policy. This strongly suggests that the public policy exemption would be triggered, and states would be free to choose for themselves whether to sanction gay marriages. At the very least it would make sense for the courts to rule on the constitutionality of DOMA and full faith and credit before amending the Constitution for only the 28th time in history.

The political reality is even more compelling: A Defense of Marriage Amendment would enshrine, for the first time, language of intolerance and exclusion in a document that was intended to set forth basic rights. Does President Bush really want to be remembered as the guy who first used the Constitution to codify bigotry? He’s walked right up to that line—signaling, most recently in his State of the Union address, that he would support such an amendment. But he need not and should not do so. The Defense of Marriage Amendment should not be on the table at all this election. Vice President Dick Cheney already made that point in the 2000 campaign, when he said that “different states are likely to come to different conclusions, and that’s appropriate.”

So what is the downside of letting Massachusetts set its own rules and letting the courts chew over the whole mess for a few years? A lack of uniformity. For a while, we’d have a crazy quilt of policies across the country, with some states permitting gay marriage and others banning it. So what? A lack of uniformity is the norm where marriage law is concerned. The only other negative, to the minds of the far right, is that some Americans might be allowed to live in states that accord them the right to marry.

We call that “federalism.”

It’s a truism to say that one of the great beauties of federalism is that states can act as mini-social-laboratories. If Massachusetts wants to recognize gay marriage, let ‘em. If Ohio wants to ban them, have at it. It’s precisely because marriage has always been reserved to the states to regulate differently that a federal constitutional amendment is so silly. But it’s even sillier for the president to make a fool of himself by amending a document that mostly gives him what he wants already—a way to keep one state from foisting its will on the others.

To amend the Constitution before the courts have even ruled on DOMA is to give in to pre-emptive hysteria. It’s a hedge against a hole in an escape hatch. It calls out only one signal: that even one gay marriage in one small state is too many. That’s not statesmanship, and it’s not political policy. It’s bigotry.